Ensemble monte carlo simulation of quantum well infrared photodetectors, and inp based long wavelength quantum well infrared photodetectors for thermal imaging

Cellek, Oray Orkun
Quantum well infrared photodetectors (QWIP) utilize quantum wells of large bandgap materials to detect infrared radiation. When compared to conventional low bandgap LWIR photodetectors, the QWIP technology offers largest format thermal imagers with much better uniformity. The theoretical part of this study includes the development of a QWIP ensemble Monte Carlo simulator. Capture paths of electrons to quantum wells are simulated in detail. For standard AlGaAs/GaAs QWIPs, at medium and high E-fields L valley quantum well (QW) is a trap for electrons which causes higher capture probability when compared with InP/InGaAs and GaAs/InGaAs QWIPs. The results suggest that high photoconductive gain observed in InP/InGaAs and GaAs/InGaAs QWIPs is not due to good transport properties of binary barrier material but due to higher -L valley energy separation. The experimental part of the study includes the fabrication and characterization of InP/InGaAs and InP/InGaAsP QWIPs and 640x512 FPAs with the main objective of investigating the feasibility of these material systems for QWIPs. The InP/InGaAs and InP/InGaAsP QWIP detectors showed specific detectivity values above 1x1010 cm.Hz1/2/W (70K, f/2, background limited). The devices offer higher allowable system noise floor when compared with the standard AlGaAs/GaAs QWIP technology. It is also experimentally shown that for strategic applications LWIR InP based QWIPs have advantages over the standard QWIP technology. The InP/InGaAs 640x512 QWIP FPA reached 36 mK average NETD value at 70 K with f/1.5 optics and 10 ms integration time. The InP/InGaAsP QWIP on the other hand yielded 38 mK NETD histogram peak at 70 K with f/1.5 optics and 5 ms integration time on 320x256 window of the 640x512 FPA.


Long wavelength mercury cadmium telluride photodiodes and focal plane arrays
Aşıcı, Burak; Beşikci, Cengiz; Department of Electrical and Electronics Engineering (2005)
This thesis reports the fabrication and characterization of long wavelength infrared mercury cadmium telluride (Hg1-xCdxTe) photodiodes and 128x128 focal plane arrays grown on lattice matched cadmium zinc telluride (Cd1-yZnyTe) substrates by metal organic vapor phase epitaxy (MOVPE). The dark current modeling of 33x33 mm2 Hg1-xCdxTe photodiodes has shown the dark current is dominated by trap assisted tunneling under small reverse bias voltages typically used to bias these detectors. The dominant dark curren...
Ensemble Monte Carlo simulation of quantum well infrared photodetectors
Memiş, Sema; Tomak, Mehmet; Department of Physics (2006)
Quantum well infrared photodetectors (QWIPs) have recently emerged as a potential alternative to the conventional detectors utilizing low bandgap semiconductors for infrared applications. There has been a considerable amount of experimental and theoretical work towards a better understanding of QWIP operation, whereas there is a lack of knowledge on the underlying physics. This work provides a better understanding of QWIP operation and underlying physics through particle simulations using the ensemble Monte...
Electrically controlled terahertz spatial light modulators with graphene arrays
Kakenov, Nurbek; Takan, Taylan; Özkan, Vedat Ali; Balci, Osman; Polat, Emre O.; Altan, Hakan; KOCABAŞ, COŞKUN (2016-05-27)
Gate-tunable high-mobility electrons on atomically thin graphene layers provide a unique opportunity to control electromagnetic waves in a very broad spectrum. In this paper, we describe an electrically-controlled multipixel terahertz light modulators. The spatial light modulator is fabricated using two large-area graphene layers grown by chemical vapor deposition and transferred on THz transparent and flexible substrates. Room temperature ionic liquid, inserted between the graphene, provides mutual gating ...
Efficient and accurate electromagnetic analysis of three-dimensional nano-optical structures
Yazar, Şirin; Sür, Cem Gürkan; Solak, Birol; Eroğlu, Ömer; Altınoklu, Aşkın; Güler, Sadri; Gür, Uğur Meriç; Karaosmanoğlu, Barışcan; Ergül, Özgür Salih (2017-07-08)
We present computational analysis of optical nanostructures, including but not limited to frequency-selective surfaces, metamaterials, nanoantennas, nanowires, and photonic crystals. A rigorous implementation based on surface integral equations and the multilevel fast multipole algorithm is developed for the analysis of such three-dimensional complex structures, without resorting to infinity, self-similarity, periodicity or homogeneity assumptions. The developed simulation environment provides accurate anal...
Diffraction-Grating-Coupled High Quantum Efficiency InP/InGaAs Quantum Well Infrared Photodetector Focal Plane Array
Arslan, Yetkin; Colakoglu, Tahir; Beşikci, Cengiz (2013-02-01)
Quantum well infrared photodetector (QWIP) is still the sole field proven low-cost long-wavelength infrared photon sensor. We report an impressively high quantum efficiency of 31% in the pixels of a large format (640 x 512) grating-coupled InP/In0.48Ga0.52As QWIP focal plane array (FPA). The InP/InGaAs QWIP FPA with a cut-off wavelength of similar to 9 mu m provided desirable characteristics at a temperature as high as 78 K. The noise-equivalent temperature difference of the FPA with f/2 optics is similar t...
Citation Formats
O. O. Cellek, “Ensemble monte carlo simulation of quantum well infrared photodetectors, and inp based long wavelength quantum well infrared photodetectors for thermal imaging,” Ph.D. - Doctoral Program, Middle East Technical University, 2006.